Process for extracting germanium monoxide



July 31, 1956 H Eo INUZUKA ET AL 2,757,068

PROCESS FOR EXTRACTING GERMANIUM MONOXIDE Filed Dec. 18, 1953 M KEG mx amuogkws INVENTORS HIDEO INUZUKA 8. KAKUZO TADA {M4 wand ite. States Patent Office Patented July 31', 1956 Ota-ku, Tokyo, Japan,

Hideo lnuzuka and Kakuzo Tada,

Kawaassignors to Tokyo Shibaura Electric Co., Ltd., saki-shi, Kanogawa-ken, Japan 1953, Serial No. 399,161 application Japan December 26,1952

Application December 18, Claims priority,

1 Claim. (Cl. 23-41) This invention relates to a process for extracting germanium monoxide or, particularly, to an extracting process sutable to obtain germanium monoxide from a silicon carbide which is contaminated with metallic germanium.

The use of germanium rectifiers and transistors.

has been developed for crystal The demand therefor has been remarkably increasing. t is necessary in such usages to cut or grind germanium. Thus a considerable amount of valuable germanium is lost as so-called chips. Germanium to be used for crystal rectifiers and transistors is doped with a slight amount of such elements as boron, aluminum, etc. as impurities to make the germanium of p-type and phosphorus, antimony, etc. as impurities to make the germanium. of n-type. Therefore, even if-germanium were recovered as it is from said chips, not be reused. As silicon carbide (SiC) is used as abrasive in working germanium in most cases, it is isadvantageous in operation to extract it coul the small amount of germanium as a chloride from the ground chip powder of said silicon carbide. That is to say, according to the hitherto existing process, there is no other way than to obtain a considerably refined product by fractionally distilling germanium tetrachloride (GeCli) obtained by of germanium contained in said ground chip then to subject said product to a segregation Germanium is chloridized usually by heating a material containing germanium in a chlorine gas flow. However, in case silicon carbide co-exists in said material, silicon tetrachloride (SiCl4) will be simultaneously produced and, as the boiling point of silicon tetrachloride is lower than that of germanium tetrachloride, there will be disadvantageous inconvenience in fractional distillation.

An object of this invention is to provide a process for obtaining germanium monoxide at a good yield from a material containing metallic germanium co-existing with silicon carbide.

Other objects of the invention will be understood from the following descriptions.

There is a lower oxidized substance, that is, germanium monoxide (GeO) as well as non-volatile germanium dioxide (GeOz) in germanium oxide. It is known that said germanium monoxide is produced by heating a mixture of equivalent amounts of germanium dioxide (GeOz) and germanium (Ge) under a reduced pressure and is considerably volatile at high temperatures above 800 C. It has been found that by heating germanium at 800 C. in an oxygen atmosphere at normal pressure, germanium dioxide is produced in the main, and that only a small quantity of germanium monoxide is formed. However,

phere at in this invention is it has also been found that germanium monoxide can be easily produced by heating germanium in an atmosa reduced pressure of an incomplete oxidizing gas obtained by mixing such an inert gas as nitrogen with oxygen.

in recovering germanium contaminated with about 1% in the powder of silicon carbide, if the reaction temperature is chosen at 900 to 1100 C. and the pressure within the reaction vessel is chosen as reduced to 10 to 40 mm. Hg, the mixed gas to be used may be either air or a mixed gas ofoxygenand nitrogen containing more oxygen than air does.

The germanium monoxide extracting apparatus used shown diagrammatically on the'accompanying sheet of drawing. The reactionvessel was a transparent fused silica tube 1 measuring 30 mm. in 2 mm. in wall thickness and 1 meter The opening atone end of the tube was air-tightly: fitted with a rubber plug 2 through which a gas inlet tube 3 provided with a cock 4 and a protecting tube 5 for thermocouple were air-tightly inserted. The opening at the other end of the tube was air-tightly fitted with a rubber plug 7 throughwhich a gas outlet tube 8 provided with a cock 9 was air-tightly inserted. The length of of said tube 1 wasmade so as to be inserted into an electric furnace 10. The materialpowder was contained in a boatv 11 made of fused. silica-,and. measuring 10 cm. in length, 2 cm. in width and 1 cm. in depth. The boat. was inserted and placed in the middle part of the tube 1, being adjacent to the tip of the thermocouple. The gas outlet tube 8 was connected with a vacuum pump. A side tube with which a manometer 12 was connected was provided so as to measure the pressure within the reaction tube 1.

In each of the following illustrative examples, this invention was applied to powdered chips obtained when germanium was worked with abrasives of silicon carbide, the germanium content being more or less than 1%.

EXAMPLE 1 of a material containing germanium were put The boat was inserted and placed in the reaction tube. First, the gas inlet tube was connected with a gas reservoir containing a mixed gas consisting of 8.5 parts by volume of nitrogen and 1.5 parts by volume of oxygen. The cock of the gas outlet tube was opened and the air within the reaction tube was replaced with said mixed gas. Said cock was then closed. Next, the gas outlet tube was connected with the vacuum pump and electric currents were fed to the electric furnace while the pressure within the tube was being reduced. When the temperature therein bcame 1000 C., the cock of the gas inlet tube was slightly opened and the mixed gas was led in. Heating was continued for 2 hours in a flow of the mixed gas while the pressure within the tube was regulated to be 2 to 3 mm. Hg by the indication of the manometer. Then the feed of the electric currents was stopped and the two cocks were closed. At this time, the temperature within the reaction tube had reached approximately 1100 C. The germaniurr dioxide contained in the powder reacted during the abovt heating. The gas containing germanium monoxide move through the reaction tube mainly to the side of the ga outlet tube and was cooled to deposit germaniur monoxide on the inside wall of the reaction tube. Hon

5 grams into the boat.

V 2,757,068 ever, a pant of germamum monoxide was deposited on EXAMPLES 2 TO 4 the inside wall of the reaction tube on the side of the Th matenal was treated m h same manner as m gas inlet tube. Example 1 he conditions as dliferent from those in T was de rmined as follows: When the reaction tube was The conditions and result in Example 1 are also enumercooled, it was taken out of the furnace. At first, a mixed ated for information.

Table I Total amount Reaction Reaction Reaction ofInfiow of Percent- Examples, Mixed Gas Temperature, Press re, Time, Mixed Gas, age of Ex- 0. mm. Hg hours liters approxitraction ate y m a 2 t0 3 2 1 73 15 to 16 2 7 69 20 to 22 2 84 25 to 30 2 90 *Parts by volume.

solution of cc. of 20% NaOH and 5 cc. of 30% 20 What we claim is:

02 was poured into the tube by fixing the rubber plug A process for xtracting germanium as germanium at the opening at one end of the tube. The deposit was monoxide from silicon carbide-containing material dissolved therein by being heated at 80 to 90 C. and comprises heating said silicon carbide material contain- Then, according to the method of G. R. Davies and G under a reduced pressure of 10 to 40 mm. Hg of a gas (1938)), the solution was treated with sulphuric acid and, nitrogen and oxygen, said mixture containing more thereafter, a tannic acid solution. A precipitate prooxygen than is contained in air, and cooling the thusduced was filtered, washed and then ignited and was thus produced gas containing germanium monoxide.

weighed as germanium dioxide. As a result, the percentage of extraction was 73%, References Cited in the file of this patent Germanium monoxide deposited on the inside wall of FOREIGN PATENTS the reaction tube can be obtained as germanium tetrachloride when heated at 40 C. by passing a chlorine gas 378017 Great Bntam July 1932 flow through the tube and can therefore be easily taken OTHER REFERENCES out and utilized. Hopkins: Chemistry of the Rarer Elements, 1923,

In order to deposit germanium monoxide, a tube published by D. C. Heath and Co., New York, pages through which a cooling medium is passed may be fixed 199 and 200.

within the reaction tube or formed so as to be free to Browing: Introduction to the Rarer Elements, 1912, insert and remove, published by John Wiley and Sons, New York, page 105. 

